cc: Stretch textures by .5 texels to prevent out of bounds sampling

cc/picture_layer_tiling.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_PICTURE_LAYER_TILING_H_
 #define CC_PICTURE_LAYER_TILING_H_
 
 #include "base/basictypes.h"
 #include "base/hash_tables.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 47 matching lines @@
   float contents_scale() const { return contents_scale_; }
 
   std::vector<Tile*> AllTilesForTesting() const {
     std::vector<Tile*> all_tiles;
     for (TileMap::const_iterator it = tiles_.begin();
          it != tiles_.end(); ++it)
       all_tiles.push_back(it->second);
     return all_tiles;
   }
 
+  enum LayerDeviceAlignment {
+    LayerDeviceAlignmentUnknown,
+    LayerAlignedToDevice,
+    LayerNotAlignedToDevice,
+  };
+
   // Iterate over all tiles to fill content_rect.  Even if tiles are invalid
   // (i.e. no valid resource) this tiling should still iterate over them.
   // The union of all geometry_rect calls for each element iterated over should
   // exactly equal content_rect and no two geometry_rects should intersect.
   class CC_EXPORT Iterator {
    public:
     Iterator();
-    Iterator(
-        const PictureLayerTiling* tiling,
+    Iterator(const PictureLayerTiling* tiling,
         float dest_scale,
-        gfx::Rect rect);
+        gfx::Rect rect,
+        LayerDeviceAlignment layerDeviceAlignment);
     ~Iterator();
 
     // Visible rect (no borders), always in the space of content_rect,
     // regardless of the contents scale of the tiling.
     gfx::Rect geometry_rect() const;
     // Texture rect (in texels) for geometry_rect
     gfx::RectF texture_rect() const;
     gfx::Size texture_size() const;
 
     // Full rect (including borders) of the current tile, always in the space
@@ skipping 67 matching lines @@
   TileResolution resolution_;
   int last_source_frame_number_;
   double last_impl_frame_time_;
 
   friend class Iterator;
 };
 
 }  // namespace cc
 
 #endif  // CC_PICTURE_LAYER_TILING_H_